Effect of Irrigation on Dry-Farmed Vitis vinifera L. cv. Zinfandel as a Function of Vine Age
Jocelyn Alvarez Arredondo, Federico Casassa, and
Jean C. Dodson Peterson*
*Wine and Viticulture Department; Horticulture and Crop Science
Department, One Grand Avenue, Building 11, Room 218, San Luis
Obispo, CA, 93407 (jdodsonp@calpoly.edu)
Natural rainfall in viticulture is often supplemented with irrigation during the dormant and active seasons. Unfortunately, rainfall events are becoming scarce and prolonged drought has dwindled water reserves. Additional information is needed on the influence of vine age on dry-farmed vine performance. This study evaluated the effect of dry farming and growing season irrigation on vine performance and fruit composition as a function of vine age in Zinfandel. The vineyard was historically dry-farmed during the growing season and received winter irrigation. Age treatments included Young vines (five to 12-years-old), Control vines (2:1 ratio of old to young, representative of the block), and Old vines (40 to 60-years-old). Within each age designate, there were irrigated and non-irrigated vines. Irrigation based on age-specific ETc was applied manually to the Irrigated treatment vines at veraison and veraison + four weeks. Irrigation did not influence vine development, except during some growth stages. Leaf abscission and chlorosis variations were significant among age and non-irrigation treatments. Shoot length varied significantly as a function of age, but not irrigation status. Stomatal conductance, photosynthetic rate, and leaf water potential showed no significant effects. Vine age influenced fresh and dry berry skin weight. Irrigated treatments had higher Brix than non-irrigated vines. Additionally, Old vines produced more fruit in both irrigation treatments (49.6 kg more irrigated; 6.8 kg in non-irrigated). This suggests irrigation added to traditionally dry-farmed vines during the growing season has minimal influence on performance. Additionally, dormant season irrigation applications are potentially enough to overshadow any notable difference imparted by irrigation events during the active season as a function of vine age.
Funding Support: CSU Agricultural Research Institute Award 21-03-101; Historical Vineyard Society; Dusi Vineyards
